1. Field of the Invention
The present invention relates to a laminated sheet heater, a laminated sheet heater with lead wire including the laminated sheet heater and a lead wire electrically connected to a heater element of the laminated sheet heater, a battery structure with heater including the laminated sheet heater or the laminated sheet heater with lead wire, and a heater unit.
2. Description of Related Art
Heretofore, various types have been proposed as a laminated sheet heater having a heater element and a laminated sheet heater with lead wire (hereinafter, referred to as a “lead wire-equipped laminated sheet heater”) including a lead wire electrically connected to the heater element (see for example JP8 (1996)-162259A and “Outline of heater products” on a website of KURABE Industrial Co., Ltd., (http://www.kurabe.co.jp/japanese/product/heater/heat.htm).
JP '259A shows, as a prior art, a lead wire-equipped laminated sheet heater in which a cylindrical metal grommet that is placed through the laminated sheet heater in its thickness direction and is electrically connectable to the heater element. The lead wire is inserted through the cylindrical metal grommet and soldered thereto to be connected to the heater element.
Further, JP '259A indicates, as a preferred embodiment, a lead wire-equipped laminated sheet heater in which a base film (an insulating resin film) is formed with an opening, through which part of a heater element (a connecting terminal portion) is drawn from the back side of the laminated sheet heater to the outside in the thickness direction, and a connecting terminal portion of the heater element is connected to a lead wire in a place outside of the back side of the laminated sheet heater in the thickness direction.
The KURABE's website discloses a lead wire-equipped laminated sheet heater in which a heater element and a lead wire is connected outside of the laminated sheet heater in its planar direction parallel to the surface of the heater.